TY  - JOUR
PY  - 2014//
TI  - Gradual unlocking of plate boundary controlled initiation of the 2014 Iquique earthquake
JO  - Nature
A1  - Schurr, Bernd
A1  - Asch, Günter
A1  - Hainzl, Sebastian
A1  - Bedford, Jonathan
A1  - Hoechner, Andreas
A1  - Palo, Mauro
A1  - Wang, Rongjiang
A1  - Moreno, Marcos
A1  - Bartsch, Mitja
A1  - Zhang, Yong
A1  - Oncken, Onno
A1  - Tilmann, Frederik
A1  - Dahm, Torsten
A1  - Victor, Pia
A1  - Barrientos, Sergio
A1  - Vilotte, Jean-Pierre
SP  - 299
EP  - 302
VL  - 512
IS  - 7514
N2  - On 1 April 2014, Northern Chile was struck by a magnitude 8.1 earthquake following a protracted series of foreshocks. The Integrated Plate Boundary Observatory Chile monitored the entire sequence of events, providing unprecedented resolution of the build-up to the main event and its rupture evolution. Here we show that the Iquique earthquake broke a central fraction of the so-called northern Chile seismic gap, the last major segment of the South American plate boundary that had not ruptured in the past century. Since July 2013 three seismic clusters, each lasting a few weeks, hit this part of the plate boundary with earthquakes of increasing peak magnitudes. Starting with the second cluster, geodetic observations show surface displacements that can be associated with slip on the plate interface. These seismic clusters and their slip transients occupied a part of the plate interface that was transitional between a fully locked and a creeping portion. Leading up to this earthquake, the b value of the foreshocks gradually decreased during the years before the earthquake, reversing its trend a few days before the Iquique earthquake. The mainshock finally nucleated at the northern end of the foreshock area, which skirted a locked patch, and ruptured mainly downdip towards higher locking. Peak slip was attained immediately downdip of the foreshock region and at the margin of the locked patch. We conclude that gradual weakening of the central part of the seismic gap accentuated by the foreshock activity in a zone of intermediate seismic coupling was instrumental in causing final failure, distinguishing the Iquique earthquake from most great earthquakes. Finally, only one-third of the gap was broken and the remaining locked segments now pose a significant, increased seismic hazard with the potential to host an earthquake with a magnitude of >8.5.<p/>  <p>Language: en</p>
LA  - en
SN  - 0028-0836
UR  - http://dx.doi.org/10.1038/nature13681
ID  - ref1
ER  -